1. Field of the Invention
Embodiments of the invention generally relate to a method and apparatus for conditioning a polishing pad.
2. Description of the Related Art
Chemical Mechanical Planarization (CMP) and Electrochemical Mechanical Planarization (ECMP) are a techniques utilized to planarize a substrate during integrated circuit fabrication. Both techniques move a substrate laterally against a processing pad during processing in the presence of a processing fluid.
The processing pad must have the appropriate mechanical properties for substrate planarization and bulk removal while minimizing the generation of defects in the substrate during polishing. Such defects may be scratches in the substrate surface caused by raised areas of the pad or by polishing by-products disposed on the surface of the pad, such as abraded portions of the pad, agglomerations of abrasive particles from a polishing slurry, removed materials from the substrate, and the like. The processing pad generally deteriorates naturally during polishing due to wear and/or accumulation of polishing by-products on the pad surface. Thus, the pad surface must periodically be refreshed, or conditioned, to restore the performance of the pad. Conventionally, an abrasive conditioning disk is used to work the top layer of the pad surface into a state that possesses desirable polishing results. However, conventional conditioning processes that aggressively interact with the pad may have an adverse affect on the pad lifetime. Additionally, conditioning uniformity is difficult to achieve as one portion of the abrasive disk may dress the pad at a rate different than another portion of the disk. This may be due to unequal or non-uniform pressure applied between the pad and conditioner, poor conditioner planarity, non-uniform distribution of abrasives on the conditioner's working surface, or combinations thereof. As pads utilized in ECMP processes are generally softer than conventional CMP pads, problems conditioning ECMP pads are aggravated.
Therefore, there is a need for an improved method and apparatus for conditioning processing pads.